This invention relates to methods and apparatus for selectively controlling the temperature of a surface, and more particularly to a roller adapted to cool or heat a surface as it is rolled thereover and to methods for the utilization of such roller.
There are numerous applications, both in medically related fields, and in industry where a need exists to cool or heat a surface, for example a patient""s skin, to a selected temperature either to achieve a desired therapeutic or other result, to precool the surface prior to the performance of some other procedure which normally causes heating of the surface, the precooling reducing pain and raising the damage threshold of the surface during such procedure, or to preheat the surface prior to the performance of another procedure to facilitate the performance of such procedure. For example, in the medical area, cooling of the surface of the patient""s skin may be desirable in the early treatment of mild burns, to at least partially numb the skin to reduce pain or itching or for some other purpose. Rapid cooling of a surface may also be desirable in certain industrial applications.
However, the cooling of a surface is most useful in medical or industrial applications where a treatment to be applied either to or preferably through such surface results in the heating thereof. Precooling the skin surface in such applications can reduce pain and raise the damage threshold for the skin. For example, where a laser or other optical radiation source is applied to a patient""s skin to perform dermatology procedures such as hair removal, treatment of vascular or pigmented lesions, skin rejuvenation and the like, it is desirable that at least the epidermis of the patient""s skin be precooled to a temperature below normal body temperature, approximately 37xc2x0 C., to reduce patient pain and discomfort and to protect the epidermis from thermal damage. Depending on the procedure performed, such precooling may be adequate to protect the patient""s skin without requiring additional cooling during the performance of the procedure. In any event, such precooling will enhance the effectiveness of cooling provided during the performance of the procedure and/or reduce the thermal load imposed on any cooling mechanism operable during the performance of the procedure. There are also applications where post-cooling of a surface (ie, cooling of a surface after treatment) may be desirable to, for example, reduce pain, reduce thermal damage and/or reduce swelling.
Numerous procedures have been employed in the past for cooling or precooling the surface of a patient""s skin or other surface, for example putting an ice cube, ice pack or the like in contact with such surface, spraying such surface with a cryogen fluid or placing a device cooled thermoelectrically or by a flowing fluid in contact with the surface to be cooled. However, ice cubes are messy and may result in a water barrier between the solid ice and the skin which impedes cooling. Ice bags generally do not cool uniformly, have limited cooling capacity and thaw relatively quickly. Further, as the ice thaws, ice is less likely to be in contact with the portion of the ice bag in contact with the person""s skin, thereby significantly reducing the effectiveness of the ice bag as a cooling medium. Cryogen in contact with the patient""s skin may result in the skin being cooled below the desired temperature and this form of cooling is not easy to control. The other forms of contact cooling are generally more complex and expensive, both to purchase and to use, and are therefore not ideal for many applications; in particular, they generally are not suitable for quickly covering a large surface area.
Similarly, heating of a surface is frequently utilized to perform a selected therapeutic function, such as for relief of muscle aches or to relax collagen coils to permit reconfiguration of skin features such as wrinkles. Preheating of skin or another surface may be utilized to facilitate a heat treatment procedure to be subsequently performed by a radiation or other heating source, for example permitting a lower power source to be used for such function or permitting greater control in the performance of such function.
Heating or cooling may also be used in conjunction with massage to treat muscle, joint and other problems.
A need therefore exists for an improved mechanism for quickly cooling, precooling, heating, preheating, post-cooling or post-heating a surface, in particular the surface of a patient""s skin, over a relatively large area to a substantially uniform and relatively controlled temperature, which mechanism is both easy to use and relatively inexpensive. In some applications, particularly where the surface is a patient""s skin, it may also be desirable to apply pressure to the skin in conjunction with the temperature control function so as to temporarily remove blood from the treatment area, thereby reducing the moderating effect of profusion on the desired temperature change. Pressure may also perform a massage function which may be desirable in certain applications, particularly for the treatment of sore muscles or other aches and pains. Further, there is frequently a need to spread a thin layer of an impedance matching liquid or of some other substance over the patient""s skin or other surface prior to treatment. It would be desirable if the same mechanism used to cool or heat the patient""s skin could also be utilized to facilitate the uniform spreading of a thin layer of such substance over the surface.
In accordance with the above, this invention provides, in accordance with one aspect thereof, a device for cooling or otherwise controlling the temperature of a surface, which device includes a roller formed of a material having good heat transfer properties, for example a metal such as copper or aluminum, the roller having an external surface, which may be cylindrical, may have a plurality of faces, for example flat faces, or may have some other shape; and at least one internal surface adapted to be in contact with a medium undergoing a phase change at a temperature close to the temperature at which the surface is to be controlled. The phase change may either result in the generation of heat if the temperature of the surface is to be raised or the absorption of heat if the temperature of the surface is to be lowered. The device also includes a handle which, when connected to the roller, facilitates the rolling of the roller over the surface to be cooled. For preferred embodiments, the heat absorbing phase change is from solid to liquid, the medium for preferred embodiments being at least primarily water. The heat generating phase change may be from liquid to solid. For such embodiments, the roller may have a plurality of channels extending therethrough, the at least one internal surface being the walls of such channels. For preferred embodiments, there is a substantial number of such channels, each of which extend substantially parallel to the axis of the roller.
For alternative embodiments, the roller has a single channel formed therethrough, which channel is substantially parallel to the axis of the roller, and a mechanism is provided for chilling the walls of the channel. This mechanism may include a source of cryogen fluid and a mechanism for selectively applying the cryogen fluid to the walls of the channel, the fluid evaporating to chill such walls. The walls of the channel for this embodiment may be formed of a porous material and provide a greater surface area for chilling. Alternatively, the channel through the roller may contain at least two materials separated by a removable barrier, and materials undergoing an endoergic reaction when in contact with each other, which reaction results in the absorption of heat from the walls of the channel in contact therewith. Where the roller is being used to heat the surface, the two materials utilized might be ones which undergo an exothermic reaction when in contact with each other, which reaction results in the generation of heat to the internal surface(s). The barrier may for example be removable by being breakable and the materials utilized for this embodiment when used for cooling may be water and a suitable salt, the channel walls being of a corrosion resistant material where a salt is utilized. End caps may also be removably attachable to seal each end of the roller, with the handle being attachable to such end caps.
A temperature sensor may also be provided for the external surface, the temperature sensor for example being a temperature sensitive strip affixed to the external surface of the roller, a characteristic of the strip varying with temperature, or a thermocouple may be embedded in the external surface. A display may also be provided for the temperature sensor, the display for example being positioned in one of the end caps.
The invention also includes a method for manufacturing a cooling roller of a material having good heat transfer properties and a plurality of channels extending therethrough to cool a surface, the method including: filling the channels with a freezable liquid, freezing the liquid in the channels, the liquid expanding as it freezes, removing excess frozen liquid and sealing the roller at each of its ends. The roller is utilized by rolling the roller over the surface to be cooled, the liquid in the channels contracting as the liquid thaws to generate a partial vacuum which further facilitates the sealing of the roller. The rolling of the roller over the surface may be repeated as required to achieve a desired cooling, and/or the roller may after a period of use, be refrozen as required for subsequent use.
The invention also includes a method for controlling the temperature of a patient""s skin which includes providing a roller having a material contained therein and in contact with at least one internal surface of the roller, which material is in a state which causes the roller to be at a temperature close to the temperature to which the patient""s skin is to be controlled; and rolling the roller over a surface of the patient""s skin at a rate so as to bring the skin surface to the controlled temperature, the material selectively undergoing a state change as the roller is being rolled over the skin surface. The material may initially be in a solid, frozen state and undergo a gradual change to a liquid state during the rolling step, the surface of the patient""s skin being cooled during the rolling step to either precool the skin for a therapeutic treatment, to post-cool the skin after a therapeutic treatment or to perform a therapeutic treatment. Alternatively, the material may be initially in a heated liquid state and undergo a gradual change to a solid state during the rolling step to either preheat the surface of the patient""s skin for a therapeutic treatment or to heat the surface of the patient""s skin to perform a therapeutic treatment. Post-heating may also be performed. The rolling step may be performed under pressure resulting in at least some massaging of the patient""s skin. For a particular embodiment, two rollers are provided, which rollers may be on the same handle, each having a material therein which is in a different state, the material in one roller heating the roller and the material in the other roller cooling the roller, the rollers being alternately rolled over an area of the patient""s skin during the rolling step.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings, the same or similar reference numeral being used for like elements in the various figures.